The invention relates to a transparent pane arrangement with variable transmission properties for visible light and/or thermal radiation. Such pane arrangements are generally used in and on buildings, but also in vehicles, in order specifically to influence glare phenomena, shading and transparency, but also to reduce heating up of the building interior or of the vehicle cabin by incident insolation. Again, the incidence of directly visible insolation in the respective interior is reduced, and a dazzling effect on people present in the space is thereby avoided. In addition, such a pane arrangement can also generally be used to influence the conditions of illumination and shading.
Numerous transparent pane arrangements with variable transmission properties are already known. For example, DE 38 07 598 A1 discloses a pane arrangement having two transparent panes which are arranged parallel to one another and on whose mutually facing surfaces a grid-like coating with increased reflection properties is applied in each case. One of the panes is arranged in a stationary fashion, and the other can be displaced, with the result that the individual grid bar elements either can be aligned in a covering fashion or can be arranged offset relative to one another, the pane arrangement being opaque in the case of offset arrangement, and transparent in the case of alignment in a covering fashion. Because of the panes which move relative to one another, such a pane arrangement is complicated in design and therefore expensive to produce.
One example for a glass pane having a whole-area coating by means of a layer made from electrochromic material is, for example, disclosed in DE 35 31 443 A1. However, this pane has the disadvantage that it darkens uniformly and completely upon activation of the electrochromic layer. Although, to be precise, the incidence of solar radiation is reduced, there is simultaneously a sharp reduction in the totality of the light entering the space in the building or the vehicle, so that it may be necessary to switch on artificial light in the building space although it is broad daylight outside.
It is therefore the object of the invention to specify a transparent pane arrangement with variable transmission properties for visible light and/or thermal radiation, which on the one hand effectively decreases the penetration of direct, dazzling solar radiation, but on the other hand keeps the darkening of the respective interior within acceptable limits and lets through sufficient daylight. It is also an object of the invention to specify a transparent pane arrangement which permits individually prescribable control of the conditions of illumination and shading.
This object is achieved by means of the transparent pane arrangement specified in claim 1.
By virtue of the fact that the transmission property of individual strips can be selectively varied, the two strip-like layers made from the material with variable transmission properties renders it possible to achieve a screening effect which ensures reflection and/or absorption of radiation which strikes the pane at a first angle of incidence, while it is immediately possible to look through the pane at a different angle, thus also directly possible for scattered light to pass through the pane arrangement. The result of this is to prevent people located in the interior from being dazzled directly by insolation, while it is possible both for daylight to fall into the interior, and for the pane arrangement to be looked through.
The pane arrangement according to the invention also permits the conditions of illumination and shading to be set individually, by virtue of the fact, for example, that only a prescribed region of the pane is provided with the strip-shaped layers made from the material with variable transmission properties, or by virtue of the fact that the strip-shaped layers are activated only in a prescribed region.
The substrate is preferably designed as a flat panel, but it can also have a shape which is spherically curved or formed with sharp edges.
Advantageous developments of the invention are specified in the subclaims, it being advantageous, in particular, when two layers are provided which are arranged on two mutually averted surfaces of the transparent substrate.
As an alternative thereto, it is, however, also possible to provide two mutually spaced transparent substrates in the case of which the layers are respectively arranged on mutually facing surfaces of the transparent substrates.
In a further alternative refinement, a plurality of transparent substrates and more than two layers are provided, the layers being arranged on mutually spaced surfaces of the transparent substrates. This embodiment permits activation of differently spaced layers to be used to undertake optimum adaptation to the angle of incidence of the radiation to be reflected.
It is advantageous, furthermore, when the strips made from the material with variable transmission properties are arranged essentially horizontally when the pane is located in its prescribed installation alignment. This horizontal arrangement of the strips is advantageous, in particular when the sun stands very high, and thus in the case of a steep angle of incidence of the rays, and also in the case of rays which are incident on the pane arrangement essentially perpendicularly or at a blunt angle (measured in the horizontal plane).
The installation alignment of the pane arrangement is preferably perpendicular.
In an alternative embodiment, which is preferably suitable for oblique windows, the prescribed installation alignment is oblique and the pane is designed for a roof window.
In a simple embodiment, the pane arrangement is constructed such that the material with variable transmission properties automatically decreases the transmission and increases the reflection in the presence of insolation. This can be achieved, for example, by phototropic layers, the layer directed toward the outside either being invariable, with the result that the strips are, for example, printed onto the substrate by means of screen printing, and the strips of the layers situated further inward being activated automatically by the residual insolation.
However, it is particularly preferred when the material with variable transmission properties is an electrochromic material, which decreases the transmission and increases the reflection when an electric voltage is applied. This embodiment permits individual adaptation of the reflection and transmission properties to the respective application.
It is advantageous, in addition, to provide a control device having a radiation sensor for the electrochromic material, the transmission properties then being controlled as a function of the radiation intensity received by the radiation sensor.
It is, moreover, advantageous when the width of the individual strips is variable by virtue of the fact that a plurality of juxtaposed strips are combined to form a multiple strip. It is thereby possible to undertake adaptation to the angle of incidence of the direct insolation.
The layer made from electrochromic material preferably comprises a multiplicity of strips or multiple strips arranged juxtaposed in parallel in pairs, it being possible for each strip or each multiple strip of a pair to be driven individually in order to vary its transmission properties.
It is preferred in this case that in each case first strips or multiple strips and in each case second strips or multiple strips of the individual pairs of the strips or multiple strips made from electrochromic material are arranged juxtaposed alternately, and the first strips or multiple strips and the second strips or multiple strips can respectively be driven in common in order to vary the respective transmission properties. In this way, the type of double louver having alternatingly reflecting and transmitting strips is created.
If the strip-shaped layers made from electrochromic material are arranged in groups which can respectively be driven individually, and can thereby have their transmission properties varied, the strip-shaped layers of the pane arrangement can also be activated only partially as required.
In a simplified embodiment, the layers made from the material with variable transmission properties can also be provided only in a subregion of the pane arrangement.
In order to protect the layer made from the material with variable transmission properties against external mechanical effects, for example owing to rain or hail or other mechanical influences, a protective layer made from a transparent material can be applied to each of the layers provided outside on the transparent substrate.